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information-schema-tiflash-segments.md

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TIFLASH_SEGMENTS
Learn the `TIFLASH_SEGMENTS` information_schema table.

TIFLASH_SEGMENTS

Warning:

Do not use this table in production environments, as the fields of the table are unstable, and subject to change in new releases of TiDB, without prior notice.

The TIFLASH_SEGMENTS table provides statistical information about data tables in TiFlash.

USE information_schema;
DESC tiflash_segments;
+-------------------------------+-------------+------+------+---------+-------+
| Field                         | Type        | Null | Key  | Default | Extra |
+-------------------------------+-------------+------+------+---------+-------+
| DATABASE                      | varchar(64) | YES  |      | NULL    |       |
| TABLE                         | varchar(64) | YES  |      | NULL    |       |
| TIDB_DATABASE                 | varchar(64) | YES  |      | NULL    |       |
| TIDB_TABLE                    | varchar(64) | YES  |      | NULL    |       |
| TABLE_ID                      | bigint(64)  | YES  |      | NULL    |       |
| IS_TOMBSTONE                  | bigint(64)  | YES  |      | NULL    |       |
| SEGMENT_ID                    | bigint(64)  | YES  |      | NULL    |       |
| RANGE                         | varchar(64) | YES  |      | NULL    |       |
| EPOCH                         | bigint(64)  | YES  |      | NULL    |       |
| ROWS                          | bigint(64)  | YES  |      | NULL    |       |
| SIZE                          | bigint(64)  | YES  |      | NULL    |       |
| DELTA_RATE                    | double      | YES  |      | NULL    |       |
| DELTA_MEMTABLE_ROWS           | bigint(64)  | YES  |      | NULL    |       |
| DELTA_MEMTABLE_SIZE           | bigint(64)  | YES  |      | NULL    |       |
| DELTA_MEMTABLE_COLUMN_FILES   | bigint(64)  | YES  |      | NULL    |       |
| DELTA_MEMTABLE_DELETE_RANGES  | bigint(64)  | YES  |      | NULL    |       |
| DELTA_PERSISTED_PAGE_ID       | bigint(64)  | YES  |      | NULL    |       |
| DELTA_PERSISTED_ROWS          | bigint(64)  | YES  |      | NULL    |       |
| DELTA_PERSISTED_SIZE          | bigint(64)  | YES  |      | NULL    |       |
| DELTA_PERSISTED_COLUMN_FILES  | bigint(64)  | YES  |      | NULL    |       |
| DELTA_PERSISTED_DELETE_RANGES | bigint(64)  | YES  |      | NULL    |       |
| DELTA_CACHE_SIZE              | bigint(64)  | YES  |      | NULL    |       |
| DELTA_INDEX_SIZE              | bigint(64)  | YES  |      | NULL    |       |
| STABLE_PAGE_ID                | bigint(64)  | YES  |      | NULL    |       |
| STABLE_ROWS                   | bigint(64)  | YES  |      | NULL    |       |
| STABLE_SIZE                   | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES                | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES_ID_0           | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES_ROWS           | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES_SIZE           | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES_SIZE_ON_DISK   | bigint(64)  | YES  |      | NULL    |       |
| STABLE_DMFILES_PACKS          | bigint(64)  | YES  |      | NULL    |       |
| TIFLASH_INSTANCE              | varchar(64) | YES  |      | NULL    |       |
+-------------------------------+-------------+------+------+---------+-------+
33 rows in set (0.00 sec)

Fields in the TIFLASH_SEGMENTS table are described as follows:

  • DATABASE: Database name in TiFlash. The segment belongs to a table in this database.
  • TABLE: Table name in TiFlash. The segment belongs to this table.
  • TIDB_DATABASE: Database name in TiDB. The segment belongs to a table in this database.
  • TIDB_TABLE: Table name in TiDB. The segment belongs to this table.
  • TABLE_ID: The internal ID of the table to which the segment belongs. This ID is unique within a TiDB cluster.
  • IS_TOMBSTONE: Indicates whether the table the segment belongs to can be recycled. 1 indicates that the table can be recycled. 0 indicates that the table is in a normal state.
  • SEGMENT_ID: Segment ID, which is unique within a table.
  • RANGE: The range of data that the segment contains.
  • EPOCH: The updated version of the segment. The version number of each segment increases monotonically.
  • ROWS: The total number of rows in the segment.
  • SIZE: The total size of the segment data (in bytes).
  • DELTA_RATE: The ratio of the total number of rows in the Delta layer to that in the segment.
  • DELTA_MEMTABLE_ROWS: The total number of cached rows in the Delta layer.
  • DELTA_MEMTABLE_SIZE: The total size of the data cached in the Delta layer (in bytes).
  • DELTA_MEMTABLE_COLUMN_FILES: The number of Column Files cached in the Delta layer.
  • DELTA_MEMTABLE_DELETE_RANGES: The number of Delete Ranges cached in the Delta layer.
  • DELTA_PERSISTED_PAGE_ID: The ID of the data stored on a disk in the Delta layer.
  • DELTA_PERSISTED_ROWS: The total number of rows of persisted data in the Delta layer.
  • DELTA_PERSISTED_SIZE: The total size of the persisted data in the Delta layer (in bytes).
  • DELTA_PERSISTED_COLUMN_FILES: The number of persisted Column Files in the Delta layer.
  • DELTA_PERSISTED_DELETE_RANGES: The number of persisted Delete Ranges in the Delta layer.
  • DELTA_CACHE_SIZE: The size of the cache in the Delta layer (in bytes).
  • DELTA_INDEX_SIZE: The size of the indexes in the Delta layer (in bytes).
  • STABLE_PAGE_ID: The disk storage ID of the data in the Stable layer.
  • STABLE_ROWS: The total number of rows in the Stable layer.
  • STABLE_SIZE: The total size of the data in the Stable layer (in bytes).
  • STABLE_DMFILES: The number of DMFiles in the Stable layer.
  • STABLE_DMFILES_ID_0: The disk storage ID of the first DMFile in the Stable layer.
  • STABLE_DMFILES_ROWS: The total number of rows in the DMFile in the Stable layer.
  • STABLE_DMFILES_SIZE: The total size of the data in the DMFile in the Stable layer (in bytes).
  • STABLE_DMFILES_SIZE_ON_DISK: The disk space occupied by the DMFile in the Stable layer (in bytes).
  • STABLE_DMFILES_PACKS: The number of Packs in the DMFile in the Stable layer.
  • TIFLASH_INSTANCE: The address of the TiFlash instance.